Ball screw



FIG. 1 is a perspective view of a ball screw.

FIG. 2 is a front elevation view thereof.

FIG. 3 is a rear elevation view thereof.

FIG. 4 is a top plan view thereof.

FIG. 5 is a bottom plan view thereof.

FIG. 6 is a left side elevation view thereof; and,

FIG. 7 is a right side elevation view thereof.

The broken lines shown in the drawings illustrate portions of the ballscrew that form no part of the claimed design.

CLAIM The ornamental design for a ball screw, as shown and described.